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(5x-1)(2x+1)-10x2=0,8 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
(5*x - 1)*(2*x + 1) - 10*x2 = 4/5
$$- 10 x_{2} + \left(2 x + 1\right) \left(5 x - 1\right) = \frac{4}{5}$$
Solución detallada
Transportemos el miembro derecho de la ecuación al
miembro izquierdo de la ecuación con el signo negativo.

La ecuación se convierte de
$$- 10 x_{2} + \left(2 x + 1\right) \left(5 x - 1\right) = \frac{4}{5}$$
en
$$\left(- 10 x_{2} + \left(2 x + 1\right) \left(5 x - 1\right)\right) - \frac{4}{5} = 0$$
Abramos la expresión en la ecuación
$$\left(- 10 x_{2} + \left(2 x + 1\right) \left(5 x - 1\right)\right) - \frac{4}{5} = 0$$
Obtenemos la ecuación cuadrática
$$10 x^{2} + 3 x - 10 x_{2} - \frac{9}{5} = 0$$
Es la ecuación de la forma
a*x^2 + b*x + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = 10$$
$$b = 3$$
$$c = - 10 x_{2} - \frac{9}{5}$$
, entonces
D = b^2 - 4 * a * c = 

(3)^2 - 4 * (10) * (-9/5 - 10*x2) = 81 + 400*x2

La ecuación tiene dos raíces.
x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

o
$$x_{1} = \frac{\sqrt{400 x_{2} + 81}}{20} - \frac{3}{20}$$
$$x_{2} = - \frac{\sqrt{400 x_{2} + 81}}{20} - \frac{3}{20}$$
Gráfica
Suma y producto de raíces [src]
suma
          _____________________________________                                                _____________________________________                                                     _____________________________________                                                _____________________________________                                        
       4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\     4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\          4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\     4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\
       \/  (81 + 400*re(x2))  + 160000*im (x2) *cos|----------------------------------|   I*\/  (81 + 400*re(x2))  + 160000*im (x2) *sin|----------------------------------|          \/  (81 + 400*re(x2))  + 160000*im (x2) *cos|----------------------------------|   I*\/  (81 + 400*re(x2))  + 160000*im (x2) *sin|----------------------------------|
  3                                                \                2                 /                                                 \                2                 /     3                                                \                2                 /                                                 \                2                 /
- -- - -------------------------------------------------------------------------------- - ---------------------------------------------------------------------------------- + - -- + -------------------------------------------------------------------------------- + ----------------------------------------------------------------------------------
  20                                          20                                                                                  20                                             20                                          20                                                                                  20                                        
$$\left(- \frac{i \sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{\sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{3}{20}\right) + \left(\frac{i \sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} + \frac{\sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{3}{20}\right)$$
=
-3/10
$$- \frac{3}{10}$$
producto
/          _____________________________________                                                _____________________________________                                        \ /          _____________________________________                                                _____________________________________                                        \
|       4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\     4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\| |       4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\     4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\|
|       \/  (81 + 400*re(x2))  + 160000*im (x2) *cos|----------------------------------|   I*\/  (81 + 400*re(x2))  + 160000*im (x2) *sin|----------------------------------|| |       \/  (81 + 400*re(x2))  + 160000*im (x2) *cos|----------------------------------|   I*\/  (81 + 400*re(x2))  + 160000*im (x2) *sin|----------------------------------||
|  3                                                \                2                 /                                                 \                2                 /| |  3                                                \                2                 /                                                 \                2                 /|
|- -- - -------------------------------------------------------------------------------- - ----------------------------------------------------------------------------------|*|- -- + -------------------------------------------------------------------------------- + ----------------------------------------------------------------------------------|
\  20                                          20                                                                                  20                                        / \  20                                          20                                                                                  20                                        /
$$\left(- \frac{i \sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{\sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{3}{20}\right) \left(\frac{i \sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} + \frac{\sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{3}{20}\right)$$
=
-9/50 - re(x2) - I*im(x2)
$$- \operatorname{re}{\left(x_{2}\right)} - i \operatorname{im}{\left(x_{2}\right)} - \frac{9}{50}$$
-9/50 - re(x2) - i*im(x2)
Respuesta rápida [src]
               _____________________________________                                                _____________________________________                                        
            4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\     4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\
            \/  (81 + 400*re(x2))  + 160000*im (x2) *cos|----------------------------------|   I*\/  (81 + 400*re(x2))  + 160000*im (x2) *sin|----------------------------------|
       3                                                \                2                 /                                                 \                2                 /
x1 = - -- - -------------------------------------------------------------------------------- - ----------------------------------------------------------------------------------
       20                                          20                                                                                  20                                        
$$x_{1} = - \frac{i \sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{\sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{3}{20}$$
               _____________________________________                                                _____________________________________                                        
            4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\     4 /                  2            2         /atan2(400*im(x2), 81 + 400*re(x2))\
            \/  (81 + 400*re(x2))  + 160000*im (x2) *cos|----------------------------------|   I*\/  (81 + 400*re(x2))  + 160000*im (x2) *sin|----------------------------------|
       3                                                \                2                 /                                                 \                2                 /
x2 = - -- + -------------------------------------------------------------------------------- + ----------------------------------------------------------------------------------
       20                                          20                                                                                  20                                        
$$x_{2} = \frac{i \sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} + \frac{\sqrt[4]{\left(400 \operatorname{re}{\left(x_{2}\right)} + 81\right)^{2} + 160000 \left(\operatorname{im}{\left(x_{2}\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(400 \operatorname{im}{\left(x_{2}\right)},400 \operatorname{re}{\left(x_{2}\right)} + 81 \right)}}{2} \right)}}{20} - \frac{3}{20}$$
x2 = i*((400*re(x2) + 81)^2 + 160000*im(x2)^2)^(1/4)*sin(atan2(400*im(x2, 400*re(x2) + 81)/2)/20 + ((400*re(x2) + 81)^2 + 160000*im(x2)^2)^(1/4)*cos(atan2(400*im(x2), 400*re(x2) + 81)/2)/20 - 3/20)